maximal oxygen uptake capacity (VO2max) can be predicted by fixed-rate step tests.

Abstract

Maximal oxygen uptake capacity (VO2max) can be predicted by fixed-rate step tests. It remains however to be analyzed what exercise intensities are reached during such tests to address medical safety. In this study, we compared the physiological response to a standardized fixed-rate step test with maximal cardiopulmonary exercise testing (CPET). Methods: 113 healthy adults executed a maximal CPET on bike, followed by a standardized fixed-rate step test one week later. During these tests heart rate (HR) and oxygen uptake (VO2) was monitored continuously. From the maximal CPET, the ventilatory threshold (VT) was calculated. Next, the physiological response between maximal CPET and step testing was compared. Results: The step test intensity was 85±24% CPET VO2max and 88±11% CPET HRmax. The step test VO2 was significantly higher when compared to CPET VT (p<0.01). In 41% of the total population, step test exercise intensities >95% CPET VO2max were noted. A greater step testing exercise intensity (%CPET VO2max) was independently related to higher body mass index, and lower body height, exercise capacity (p<0.05). Conclusions: Standardized fixed-rate step tests elicit vigorous exercise intensities, especially in small, obese, and/or physically deconditioned subjects. Medical supervision seems therefore required during these tests.